Some heart valve replacement surgeries rely on a median sternotomy or a large right thoracotomy to allow unobstructed access for introducing the heart valve prosthesis into the native valve""s annulus and for subsequent rotation of the orifice and leaflets assembly to minimize potential leaflet interference with sub-annular anatomy.
The median sternotomy or a large left thoracotomy, to gain unobstructed access into a patient""s thoratic cavity, allows the surgeon to see the patient""s heart more directly, and to have more direct instrument access for: (1) excising the natural valve tissue; (2) introducing a heart valve prosthesis into the patient""s natural valve annulus; (3) securing the prosthetic valve into position; and (4) rotating the orifice and leaflet assembly of the prosthesis to minimize interference with the heart""s subannular anatomy. However, these invasive, open-chest procedures produce a high degree of trauma, a significant risk of complications, extended hospital stay, and a painful recovery period for the patient.
Recently developing Less Invasive Surgery (LIS) techniques rely on a small intercostal thoracotomy instead of a median sternotomy or large thoracotomy to gain access to the thoracic cavity. The small intercostal thoracotomy substantially reduces the above-mentioned trauma, risk of complication, recovery time, and pain for the patient. Experience indicates the thoracotomy incision should not be spread greater than 15 mm for an intercostal insertion because deflecting the ribs to a greater dimension can result in significant pain for the patient as the nerve under the rib can be crushed and damaged.
In known related technology, a trocar, approximately 20 mm wide, is positioned in an intercostal space requiring some deflection of the ribs. A disposable low profile valve holder used with a disposable handle/introducer provides the ability to pass a heart valve prosthesis sideways through the trocar and then pivoted 90 degrees to be introduced into the mitral valve""s annulus. The handle/introducer and valve holder therefore offers no utility beyond the use of a standard endoscopic articulating mechanism attached to a currently available holder or rotator. Currently marketed handles and valve holders are used for the valve introduction, and subsequent rotation is executed with currently marketed rotators or valve holders designed to rotate the valve.
Therefore, the devices and instruments for performing percutaneous penetrations within these intercostal spaces for less-invasive heart or great vessel surgery must be simple and have a xe2x80x9clow profilexe2x80x9d. Currently marketed rotators and valve holders are too bulky to fit through this intercostal space without spreading the patient""s ribs too far, and are more complicated than necessary to simply and reliably percutaneously introduce and rotate a prosthetic valve during implantation.
Mechanical heart valve prostheses include valves having one, two or more rigid leaflets. One popular valve design for a mechanical heart valve prosthesis includes an annular valve body in which a pair of opposed leaflet occluders are pivotally mounted. The occluders are movable between a closed, mated position, blocking blood flow in an upstream direction and minimizing regurgitation, and an open position, allowing blood flow in a downstream direction. The annular valve body is surrounded by a sewing ring which permits the surgeon to suture the valve in place at the site of an excised valve.
When a valve is placed within the heart, it must be accurately oriented to maximize its function. Particularly in mechanical heart valves, the orientation of the leaflets is critical since their opening and closing pathways may otherwise impinge on the surrounding cardiac walls, the walls of arteries within which the valve is placed, or the residual valvular structures including the tendeae chordae and papillary muscles. This difficulty becomes particularly acute in the placement of a heart valve in the position of the mitral valve in the heart. When replacing this valve, a surgeon will frequently expose the posterior side of the patient""s heart and enter the heart through the wall of the left atrium and sometimes through the right atrium. It is desirable to place the valve accurately within the cramped confines of the heart while leaving room for the surgeon to sew the valve in place.
To aid in the rotation of the heart valve within a sewing ring, heart valve prosthesis rotators have been proposed heretofore. Some of these rotators have bendable metal shafts which can be bent by the surgeon interoperatively, but which will retain their bent shape, requiring significant space for proper manipulation of a heart valve engaged by the rotator. The shafts of some of these rotators are constructed of a shape-memory alloy, which construction allows the shaft to recover its original straight shape upon sterilization. The term xe2x80x9cshape-memory alloysxe2x80x9d refers to that group of metallic materials that demonstrate the ability to return to same previously defined shape and size when subjected to the appropriate thermal procedure. These materials can be plastically deformed at some relatively low temperature, and upon exposure to higher temperatures, will return their shape prior to the deformation. Rotators containing shape-memory alloy shafts can be easily positioned by bending the shaft to the desired orientation. To return the shaft to its original shape, the shaft is heated (i.e., during the sterilization process) to a temperature above the alloy""s transformation temperature.
With the increased use of less invasive cardiac surgical procedures a rotator is needed that can turn a heart valve within a very limited space. To accomplish this, a rotator must have both flexibility and torqueability (i.e., kink resistance). The rotator must have the ability to absorb large amounts of strain energy and release it as the applied strain is released.
A recent low profile mechanical valve introducer and rotator is composed of a series of coaxial cylinders which are truncated resulting in a width of 14 mm. There is also a central slot to provide clearance for the leaflets after engaging a heart valve prosthesis. The outermost cylinder acts as a stop for the introducer/rotator when it contacts the inflow edge of the orifice, therefore, limiting the application of significant load to the leaflets. The intermediate cylinder, which induces the rotation of the orifice and leaflets assembly, has an additional truncation occurring 90 degrees from the first that matches with the orifice""s internal diameter flat. Also, proximal to this truncation is a notch that helps guide the introducer/rotator into the correct alignment for full engagement into the orifice and leaflets assembly when presented at an angle to the assembly""s central axis. The intermost cylinder allows the introducer/rotator to rotate freely on the leaflets"" inflow edge which helps to guide the introducer/rotator into the correct rotational alignment for full engagement into the orifice and leaflets assembly.
This embodiment can be passed through an incision of less than 15 mm in width. It can then be used to engage a heart valve prosthesis (that has been previously positioned or xe2x80x9cbutton holedxe2x80x9d into the thoracic cavity) to introduce the prosthesis into the annulus. It can also be used to rotate the orifice and leaflets assembly to the optimum orientation after the tails of the sutures used to secure the valve are tied off. Currently marketed handles and valve holders cannot pass through a 15 mm wide incision to introduce and rotate the heart valve prosthesis. A recently developed heart valve prosthesis rotator has a flexible drive shaft. In use, the drive shaft can be bent to a desired direction but will transmit torque to a heart valve rotator head, orienting a prosthetic heart valve mounted thereon. Moreover, the shaft will return to its original shape after force is removed. The shaft may be constructed of material such as super-elastic nickel-titanium alloy, which allows the rotator to be easily sterilized for re-use.
In another embodiment, the heart valve prosthesis rotator also has an annealed stainless steel shaft which can be bent by the surgeon interoperatively. The shaft will retain its shape after bending. Surrounding the shaft we have provided a drive coil which connects a rotator head at a proximal end of the shaft to a drive knob at a distal end of the shaft and adjacent a handle. By turning the drive knob, a surgeon can turn the rotator head, thus orienting the prosthetic heart valve. Torsional motion is carried along the path defined by the bendable shaft so that the rotator head can be turned without displacing the handle of the heart valve rotator.
Therefore, what is needed is a flexible handle which can be releasably attached to the low profile introducer rotator for pushing and rotating the prosthetic heart valve into position.
One embodiment, accordingly, discloses a combination low-profile pusher-rotator releasably attachable to a flexible handle for easy insertion between adjacent ribs for proper positioning of a heart valve prosthesis with a natural valve annulus. To this end, a device for releasably holding and positioning a heart valve prosthesis includes a handle having a first end, a second end and a super elastic shaft interconnecting the first end with the second end. A connector is at the second end of the handle and includes a connector portion. A low profile pusher rotator is releasably engaged with the connector portion and includes a manually flexible release portion having engagement surfaces engaged with the connector portion.
A principal advantage of this embodiment is that attachment of the handle and the pusher-rotator is accomplished by a snap-on engagement and is also provided for quick release. The device easily engages a reusable endoscopic instrument, avoiding costly disposable valve handles such as those presently in use. The pusher-rotator easily passes through the common size 15 mm wide percutaneous intercostal incision avoiding the need to spread adjacent ribs apart. Parts are either machined or injection molded out of materials suited to the biomedical industry. Also, the device permits ease of engagement with a heart valve prosthesis for introduction into a natural valve annulus and subsequent rotation of the heart valve prosthesis for alignment of the valve orifice and leaflets without imposing damage on the leaflets.